The art has provided many ways for a direction finder (DF) to determine the direction to an RF source (target), mainly by various wave analysis procedures.
Direction finding techniques can be categorized in groups, those which find the direction of the target based on the received signal amplitude, based on the received signal phase, based on received signal timing, or those which are based on several of said attributes of the received signal.
One of the major challenges all direction-finding techniques face, in most situations, but mainly within a reflective environment, is to overcome the multipath reflections problem. Multipath reflections can cause false indications regarding the direction of the targeted RF source. Reflection of waves is expected from nearby objects, such as walls, or metallic objects. Waves transmitted from a target may be scattered and reflected from nearby objects such as wall, and arrive to the direction finder via many waves and from many directions. The reflected waves are weaker due to the following facts: (a) the reflected waves travel a loner path; (b) The reflected waves are scattered to many directions; and (c) the reflected waves from an object suffer from reflection losses. The reflected waves arrive at the DF later than the direct wave due to the longer path. These reflections are combined with the direct wave, distorting the amplitude, phase, and time of arrival of the signal. In prior art direction finding techniques that are based on measuring the signals amplitude, phase, or time of arrival, these multi-path reflections cause sever errors in the direction finding.
Amplitude-Based Direction Finding Techniques:
These direction finding techniques use one or more antennas. An example of a single antenna direction finding is a rotational directional antenna. The direction from which the received signal strength (RSS) or received signal strength indication (RSSI), or equivalent thereof is the highest, is the expected direction to the target. Amplitude based directional finders that use several antennas measure the RSS/RSSI at each antenna and calculate from these amplitude differences the Angle of Arrival (AOA) of the signal. An example for an amplitude directional finder which uses several antennas is the monopulse system.
Additional techniques assess the distance to the target, based on the signal strength, and by triangulating several measurements calculate the location or the direction to the target.
Phase-Based Direction Finding Techniques:
These directional finders use two or more antennas and measure the phase difference of the arrival of a signal in plurality of antennas and calculate from these phase differences the AOA of the signal. This group includes, for example, interferometer direction finder, correlative interferometer direction finder, passed array systems, etc.
Time-Based Directional Finder Techniques:
These directional finders are also known as TOA (Time of Arrival) type directional finders. They use two or more antennas and measure the time difference of the arrival of a signal to plurality of antennas and calculate from these differences the AOA of the signal. This group includes, for example short and long base TOA, DTOA (Differential Time of Arrival) etc.
Monopulse DF Techniques:
This technique is mainly used in ELINT (Electronic Intelligence) systems and radars, to find the direction from which a pulsed radar signal or echo is received. The signal is received in two or more directional antennas. The signals in the antennas, usually highly directional antennas, are added in phase to create a sum (Σ) signal, and added in opposite phase to create a Difference (Δ) signal, in one or two dimensions, azimuth, elevation or both. Based on the Σ and Δ signal strengths, the direction of the target is determined.
All said prior art techniques rely on one or more properties of the received signal, and therefore require relatively complicated calculations and analysis, and are also relatively expensive. Therefore, said techniques are generally not suitable for small size and relatively simple wireless personal devices, such as cellular phones, PDAs, digital cameras, remote-control devices. Such devices are small in size, are provided in many cases with two or more simple omni directional or very low gain directional antennas, and are relatively of low cost. Furthermore, in many cases such devices comprise of only one receiving channel for each antenna, and therefore are not suitable for using the abovementioned prior art techniques, unless significantly increasing their size, and or price.
WO 2009/147662 by same applicants and inventors provides a direction finding technique and device that are invulnerable to reflections of the signal from nearby objects, such as walls. WO 2009/147662 also provides a direction finding technique and device, for determining those wireless communicating devices (hereinafter “target devices”) that are located within a predefined direction sector of interest. Said publication also provides such direction finding technique and device that are simple and reliable. WO 2009/147662 also provides a direction finding technique and device that do not depend on attributes of the signal such as its amplitude, phase, or time of arrival. WO 2009/147662 also provides a direction finding technique and device that can further discriminate between wireless communicating devices that are located at the front and those that are located at the back of the device. WO 2009/147662 also provides such direction finding technique and device that are compact in size, and therefore well adapted to small and relatively cheap personal devices, such as cellular phone, PDAs, digital camera, remote controls, etc. The system, device and technique of technique of WO 2009/147662 is simple and reliable.
WO 2009/147662 can determine only whether a target is located within a predefined sector, however it does not provide a radar-alike (i.e., direction, distance and elevation difference of each target in relation to the DF) display of one or more targets that are located within the communication range. WO 2009/147662 also does not teach a system method and device which can determine the three dimensional (3D) direction distance and location of multiple target devices that are located within the communication range. WO 2009/147662 also does not teach a system method and device that can determine the elevation of multiple target devices that are located within the communication range.
In another aspect, Location-Based Services (LBS) have become a common service these days, mainly in mobile electric devices such as cellular phones, navigation devices, tablet computers, and even digital cameras. A key element of LBS is the ability to determine the location of a user of an electronic device. This location is determined using location determination systems such as GPS, Wi-Fi positioning systems, cell-ID, RFID real-time location systems (RTLS), etc. Upon determination of the location of the user within by the location determination system, the location can be coupled to a graphical layout of the area—i.e., a map, and displayed. By monitoring more than one user, or by receiving an updated data by users regarding their location, as determined by location determination systems, services have evolved to utilize the location data. Users can operate features of social networking application, commerce, navigation, gaming and more.
In many cases, a key goal of LBS is to offer users proximity-related information. For example, a user of a LBS social network application can see other users that are presently located miles away, but it is more than likely that he would like to find out who is in his immediate proximity, i.e., 100-200 m range. However, ALL the prior art LBS depend on location determination systems that are external of the mobile device, and cannot function without them. Therefore, in addition to such LBS, a new type of services has emerged, called Proximity-Based Services (PBS). Some PBS are based on the direct wireless communication between electronic devices and not on location determination systems (see Wi-Fi Direct™, FlashLinQ™, Bluetooth, etc). The proliferation of wireless communication devices in general, and the integration of short-range wireless communication components (such as, but not limited to Wi-Fi, Bluetooth, NFC, RFID, Wi-Max, etc.) into electronic devices, enable broadcasting and sharing of data and communication directly between devices, i.e., not via a relay such as a router or a central server. For example, Bluetooth enables direct wireless communication between at least 2 devices. Wi-Fi Ad-hoc mode enables the creation of network devices without the use of a router. Also, an upcoming standard called Wi-Fi Direct™ will enable Wi-Fi equipped electronic devices to easily create direct wireless communication between them. Key element for these examples is that they need to be in proximity to one another, i.e., within a direct wireless communication range from one another, otherwise they cannot establish direct wireless communication. This differs from relay-based wireless communications, in which electronic devices can be within the wireless communication range of the same router (for example) but not necessarily directly with one another. By determining direction and/or distance and/or height difference between electronic devices, utilizing the direct wireless communication between the devices, PBS can be provided without the need to use location determination systems. A user may wish to find direction and/or distance and/or height difference from his device to at least one another user in his proximity. By establishing direct wireless communication with electronic devices in his proximity, the user may wish to see WHAT electronic devices are near him (i.e., what is known as “Discovery”), and WHO the users are. By using direction-finding methods and techniques, the user may be able to see the directions from him to other users or electronic devices. Same goes for distance and height difference measurement. The key element here is that no location determination system is used, and directions and/or distances and/or height differences are relative between the electronic devices and can be determined without the use of any supporting location determination system and/or third party database and/or map and/or infrastructure. The methods and illustrations described hereunder aim to cover all possible scenarios, even ones not explicitly described, in which there is a direct wireless communication between at least 2 wireless communication devices. The invention described hereunder utilizes the common availability of wireless communications such as (but not limited to) Wi-Fi or Bluetooth which exists in almost any electronic device today, together with the growing integration of Tilt sensors, such as accelerometers, Gyroscopes, or digital compasses into these devices.
As will be demonstrated, the invention uses a direct wireless communication, or direct P2P wireless communication between electronic devices, in which at least one is a direction finding (DF) device and at least one is a target, without the use of any external location determination system. Said wireless communication can be performed without any applicable wireless communication protocol.
US 2010/0070758 entitled “Group Formation Using Anonymous Broadcast Information” discloses definition of a group as one or more devices that are in transmission range of each other for a period of time, referred to as a “contact time.” The users associated with the devices in the Group are referred to as Group members. Us 2010/0279768 entitled “Game With Direction Aware Device” discloses a gaming with Co-Located, Networked Direction and Location Aware Devices a gaming system on an iPhone that can create an augmented reality by using the device's camera and sensing the device's location and orientation. U.S. Pat. No. 6,693,591 entitled “Method and Device for Cooperative Radio Direction Finding in Transmission”. This patent discloses the Finding of the direction using cooperative communication essentially GPS and UMTS, requiring a synchronization signal and based on time of arrival from multiple transmitters. US 2009/0219209 entitled “Location determination” the finding of devices' own location rather than other target's direction or location with respect to the device. These patents require an infrastructure of other transmitters in the area, for the DF and location process. U.S. Pat. No. 6,838,987 entitled “Vehicle Locating System” discloses vehicle location and indication of the direction by highly directional antenna and distance using RSSI. US 2010/0085257 entitled “System and Method for Direction Finding Using a Hand Held Device” Shows on the screen targets like bus station, railway station, police station etc. Only the direction is shown, found by switching between 6 antennas using Bartlett Beamformer. Sending and receiving dedicated data is required.
It is therefore an object of the present invention to provide a system method and device that present a radar-alike display in which the relative location of each target with respect to the location of a direction device, is displayed, whether in 2D or 3D.
It is therefore another object of the present invention to provide a system method and device for determining the 3D direction distance and elevation difference of multiple target devices that are located within the communication range.
It is another object of the present invention to provide a system method and device for determining the 3D relative location of multiple target devices that are located within the communication range, that are invulnerable to reflections of the signal from nearby objects, such as walls, metallic objects, etc.
It is another object of this invention to apply sensors or combinations of sensors for compensating for the orientation of the DF device at the time when the measurement is made.
It is still another object of the present invention to provide said system method and device that are simple in structure and reliable.
It is still another object of the present invention to provide said system method and device that do not depend on attributes of the signal such as its amplitude, phase, or time of arrival.
It is still another object of the present invention to provide said system method and device that are compact in size, and therefore well adapted to small and relatively cheap personal devices, such as cellular phone, PDAs, digital camera, remote controls, etc.
It is still another object of the present invention to provide said system method and device that are capable of determining a relative location between target devices that are located within the communication range.
It is still another object of the present invention to enable navigation to target devices that have been detected within the communication range.
It is another object of the present invention to display to a user in a radar alike manner at least one target device, wherein said display indicates the relative direction, distance, height, or any combination thereof relative to the DF.
It is another object of the present invention carry out all the above independently by the DF, without need of any external positioning determination systems.
It is another object of the present invention to limit (i.e., filter) the display to a selected sector, range, targets, or various other criteria that relate either to the targets or to the user geographic preferences. Targets may be filtered in a random or pre-defined order. Landmarks and Marks may also be categorized and used. For example, targets are categorized and displayed based on their types—for example, person, place, or product. Different colors, sounds and other means of graphical symbols are also used to differentiate between each type.
It is still another object of the present invention to provide means for tracking and/or monitoring changes in relative locations of one or more targets in comparison to the DF.
It is still another object of the present invention to enable a user to select at least one target and define it as a “landmark” or “mark”, that are in turn serve as additional reference to other targets.
It is another still object of the present invention to enable a user to “block” selected targets from conducting a direct wireless communication with the DF.
It is still another object of the present invention to use ID of targets prior to initiating the direction-finding, or post of such direction finding, as a part of a filter/sorting of targets.
It is still another object of the present invention to use the DF of the present invention for distributing sound to targets that are provided with speakers.
It is still another object of the present invention to use the DF for distributing data of any type, or performing various types of operations on selected targets following said targets direction, distance of height determination.
Other objects and advantages of the invention will become apparent as the description proceeds.